Cannot type pin, keypad issue

Hi, ive recently brought a android tablet which i brought off ebay "softwinerEvb, andriod 4.0.4my problem is, i have auto rotate turned OFF & a password on my tablet, however when i turn on my tablet it only shows half the keypad so i cannot type in my password which contains the numbers 1,2,3,4....how am i meant to type the password in if the keypad isnt showing fully? helpp please.